Benzothiazolone compounds which are beta-2-adrenoceptor agonists are described in WO2004/16601 and WO2006/056471. WO2005/110990 also describes benzo-condensed heterocycles as beta-2 agonists.
While beta-2 agonists have long been known for their bronchodilating properties, they are also known for their capability to produce skeletal muscle hypertrophy.
Numerous studies have focused on therapeutic applications of the anabolic properties of beta-2 agonists for ameliorating muscle wasting and improving muscle function. However, this class of compounds has also been associated with undesirable side-effects, including increased risk of adverse cardiovascular-related events. Thus, the use of beta-2 agonists in muscle wasting diseases has hitherto been limited by cardiac hypertrophy and potentially deleterious effects on cardiovascular function.
There is a need to provide new beta-2 agonists that are good drug candidates. In particular, a new beta-2 agonist should bind potently to the beta-2 adrenoceptor whilst showing little affinity for other receptors, such as e.g. the beta-1 adrenoceptor, the alpha-1A adrenoceptor, or the 5HT2C receptor, and show functional activity as an agonist. It should be metabolically stable and possess favourable pharmacokinetic properties. It should be non-toxic and demonstrate few side-effects, in particular fewer cardiac side-effects than known marketed beta-2 agonists, such as e.g. formoterol. Furthermore, the ideal drug candidate will exist in a physical form that is stable, non-hygroscopic and easily formulated.